Cereal snackfoods and compositions and methods for making the same

ABSTRACT

The invention provides cereal snackfoods of the expanded variety such as crisps and the like. The snackfoods of the invention comprise discrete cooked portions of a dough composition comprising gelatinized starch and added cereal bran other than rice bran, in which the amylolytic activity of the bran is controlled, and contain at least about 5% by weight and generally no more than about 35% by weight of oil or fat. The snackfoods may be produced from a half product comprising at least some gelatinized starch and added cereal bran by frying or by immersion in a bed of hot particulate material followed by spraying with fat or oil. Even when fried the snackfoods have a lower energy value than comparable known products; moreover they are highly palatable, and the bran content provides a useful source of fibre in any diet.

This is a continuation of co-pending application Ser. No. 750,678 filedon June 28, 1985, which is a continuation of applkication Ser. No.600,559 filed on Apr. 17, 1984, now U.S. Pat. No. 4,528,800, which is acontinuation-in-part of application Ser. No. 257,320 filed on Apr. 24,1981, now abandoned.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to expanded snackfoods such as crisps andlike foods obtained by cooking discrete portions of a dough composition.

(b) Description of the Prior Art

An essential requirement to obtain such expanded snackfoods is thatbefore cooking at least some of the starch in the dough should begelatinized. Gelatinization of the starch is typically achieved bycooking it in the wet state, whence a physical change takes place in itsstructure such that it becomes more viscous. It is believed the presenceof gelatinized starch is necessary to trap the steam produced on cookingso as to give the necessary expanded structure.

Various processes for preparing expanded snackfood products have beendescribed by Willard, Snack Foods, 62, pages 52 to 54, 1973, (see alsoU.S. Pat. Specification No. 3,997,684) and Matz, Snack Food Technology,The AVI. Publishing Company, Inc., Westport, Conn., U.S.A., pages 144 to149.

The processes using dough can generally be grouped into three categoriesand summarized as follows:

(1) The dry collett process:

In this process a thin portion of dried starch-based gel is expanded bya short immersion in hot fat or, as described in British PatentSpecification No. 2,008,924 A, by cooking in a hot bed of, for example,salt or calcium carbonate.

Typical of such a process is that disclosed in British PatentSpecification No. 888,689 which describes the manufacture of apotato-based foodstuff in which potato flour is mixed with powderedpotato starch, water is added to form a dough, and the dough is cookedso as to gelatinize the starch, the swollen dough being dried to form aproduct having a rubber-like consistency. After drying, the dough can besliced; the slices further dried, and then cooked in boiling fat toprovide potato crisps.

In another such process described in U.S. Pat. Specification No.4,140,803 starch is gelatinized by feeding an aqueous slurry containingstarch onto a hot double roller dryer, and the multilaminar filmobtained is cut into small pieces and fat fried.

In other such processes as described in, for example, British PatentSpecifications Nos. 1,358,097 and 1,484,455, a dough containing somepre-gelatinized starch is extruded through a die under conditions oftemperature and pressure which lead to further gelatinization; the smallpieces of this dried material are then fried as before.

(2) Frying a wet completely gelatinized dough:

In this process a wet dough containing about 30 to about 85% solids iscut into desired shapes, and then fried, the starch in the dough beingcompletely gelatinized before it is fried. Some of the products made inthis category are described in U.S. Pat. Specifications Nos. 3,539,356;3,297,450; 3,451,822; and 4,007,292; and Canadian Patent SpecificationNo. 871,648.

(3) Frying a wet dough containing some ungelatinized starch:

In this process the dough contains a mixture of gelatinized andungelatinized starch, and consists of from about 30 to about 70%,usually from about 40 to about 50%, by weight of solids. The dough isformed into pieces and fried. With such a dough, for example, asdescribed in U.S. Pat. Specification No. 3,997,684, the expansion isonly about 1.6 times the original volume compared with the over threetimes expansion obtained by the processes of the two previouscategories.

In the production of baked or toasted cereal products of the kind usedas breakfast foods, and in the production of biscuits and cookies, it isknown to employ a dough mixture including bran in various proportions ofup to about 100% of the product. Examples of such foods are disclosed inBritish Patent Specifications Nos. 344,055, 1,561,190 and 2,010,656 A.

In addition, British Patent Specifications Nos. 1,465,843 and 1,544,843disclose snackfoods including rice bran material, particularly in thelatter case to afford a rice cracker flavor.

Furthermore, U.S. Pat. Specification No. 2,701,200 to Huber, isconcerned with a novel puffed product which may contain bran and with aprocess of producing that product. In the Huber process heated pressurerollers are employed to solve problems encountered in the prior art bothwith puffing guns and "radiant" puffing, the product produced mainlybeing a breakfast cereal-type product which is fat- or oil-free. Whilethe earlier disclosure mentions that in place of whole grain materialsone may use selected fractions of grains and, as examples of suchfractions, selected flours, meals, farina, bran and the like--and indeedwhile, in its Example 10, the earlier disclosure employs wheat bran andoat bran along with white corn cones and yellow corn cones to give adry-mix bran content of about 18% by weight--there is no expressed orimplied appreciation of the use of added cereal bran in a snackfoodproduct. The presence of bran is incidental to the problem solved by theearlier invention in the provision of heated pressure rollers to achievea puffed product.

Also, U.S. Pat. Specification No. 3,656,966 to Ball et al, which relatesto a process for making a ready-to-eat food chip from cereal grain,includes products prepared by the disclosed process having their ownnatural bran, that is non-added bran at a level of up to no more thanabout 9% by weight. It is furthermore disclosed that in the resultingdough, the wheat particles of the wheat or rye bran are retained aftercooking and it is said that the oil content of the final product mayrange from about 25% to about 40% and preferably is about 30%. Again,however, the earlier invention is concerned with the use of a cuttingoperation to reduce the size of individual grain kernels to increasetheir total surface area and to expose the endosperm, thereby improvingthe absorption of moisture capabilities of the kernels when combinedwith water, and not specifically with the provision of a bran-containingfood. The presence of bran is again incidental to the problem solved.

Thus, in the prior art, bran-containing products can be seen to fallinto one of the following categories, namely: 1. Specialized productswith a distinctive flavor e.g. with added rice bran to impart thatflavor, 2. Fat-free products e.g. breakfast cereal products, and 3.Products including their own natural bran with relatively high oil orfat contents.

Furthermore, it might be thought that to add bran to an expandedsnackfood product as opposed say to a breakfast-food product woulddetract from the degree of expansion or lead to no expansion at all.Also, it might be thought that to add bran would lead to unacceptablyhigh levels of fat or oil, where fat or oil cooking is employed toexpand the snackfood dough.

However, I have now found surprisingly that a snackfood can be producedsuccessfully from a dough mix of predetermined volume comprisinggelatinized starch and added bran, the snackfood being both expanded toat least about 1.25 said predetermined volume and of relatively low fatcontent, provided the amylolytic activity of the bran is controlled toprevent breakdown of gelatinized starch in the dough compositionsubsequent to the formation of the dough composition to be cooked and upto cooking of the dough.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an expanded snackfoodprepared from a dough composition of predetermined volume and comprisingcooked portions of dough composition comprising gelatinized starch andadded cereal bran selected from the group consisting of wheat bran,barley bran, oat bran, rye bran, maize bran and mixtures thereof, thesnackfood containing from about 5% to about 35% by weight of oil or fatand from about 10% to about 70% by weight of bran, and having a volumeat least about 1.25 times said predetermined volume, the amylolyticactivity of the bran being controlled to minimize breakdown ofgelatinized starch in the dough composition subsequent to the formationof the dough composition to be cooked and up to cooking of the dough.

DESCRIPTION OF THE INVENTION

The expanded snackfood of the present invention is intended to be acrisps-like product. That is to say it should have a "fried" flavorimparted to it by the presence of at least about 5% by weight ofsaturated or unsaturated oil or fat, whether incorporated by frying orotherwise, e.g. by spraying onto the cooked product. In addition, thebran employed must not in itself nor in the amount in which it isemployed impart to the snackfood organoleptic properties whichsignificantly detract from a crisps-like feel and/or flavor. Thus, thebran used should not be rice bran which has a distinctive character andflavor sufficient to detract from the properties required, and it is tobe understood that the term "cereal bran" as used herein and in theclaims does not include rice bran.

Moreover, the snackfood must be expanded, that is the dough portionsfrom which it is derived must be expanded by frying or other cookingprocesses generally to at least about 1.25 times their original volume,preferably to at least about 1.5 or about 1.6 times, more preferably toat least about 2 times, e.g. about 2.5 or about 3 times their originalvolume. Surprisingly, the incorporation of bran does not lead (as wasexpected) to a crisps-like snackfood in which the expansion is kept toan undesirably low level Thus, with a product containing 50% by weightof bran the mean expansion may be, for example, about 1.5 times.

The present snackfood is highly palatable and can contain a high contentof bran, generally a content higher than that present in whole wheatflour (about 9% by weight of bran), and always a content higher than thenatural content of whatever starch source is employed. Generally,therefore, the snackfood of the invention comprises at least about 10%by weight of bran, for example, from about 15 to about 70% by weight ofbran, and preferably from about 20 to about 50% by weight of bran. Theinclusion of bran in a snackfood provides a highly palatable means ofincluding fiber in a diet, the necessary level of fiber often lacking inthe diets of Western populations.

It is a particularly surprising feature of the present snackfood that ithas a high palatability, both from the point of view of taste and oftexture. The snackfood while still being a crisps-like product differsfrom conventional potato crisps in being harder to bite, and thusaffords a "crunchy" feel, which provides much more oral satisfaction.Moreover, while many bran products are disliked because of a heavy branflavor, surprisingly the inclusion of bran in the present snackfoodgives a more pleasant "proteinaceous" flavor than in otherbran-containing products.

The snackfood of the invention may be in any of the many usual discreteportion forms. Thus, for example, it may be in the form of thin waferssuch as crisps, or in the form of rings, straws, chips, small"sausages", cones and the like.

The gelatinized starch may be used alone or in admixture withungelatinized starch and may be incorporated in the dough in anyconvenient form. Thus, at least some of the starch may bepre-gelatinized or at least some of the starch may be gelatinized bycooking once the dough composition has been prepared. By way of example,the starch may be one obtained from wheat, oats, barley, rye, maize,rice, cassava, potatoes, tapioca, sago, legumes and arrowroot.Preferably, the starch is one provided by incorporating a cereal flour,in particular wheat flour, in the dough. In an especially preferredaspect the wheat flour is one in which the starch has beenpre-gelatinized, e.g. one made by taking white wheat flour, making itinto a slurry with water, and then spraying the mixture onto hotrollers. The dried material is scraped off and remilled to give a finepowder which can later be reconstituted with water into a dough. Asimilar technique can be applied to flours from sources other than wheatto afford the necessary pre-gelatinized material.

In another preferred aspect, the gelatinized starch is provided bydehydrated cooked potatoes.

Preferably the cereal bran used in the present invention is wheat bran.However, other forms of cereal bran may be used where these areavailable and can produce the desired fiber content, for example,barley, oats, rye or maize bran.

Commercially available bran is the residue left over from the milling ofgrain to produce flour, and comprises the grain husk with varying butrelatively small amounts of adhering endosperm. Thus, wheat bran isavailable as coarse bran, middlings (or weatings) and superfine weatingswhich respectively comprise up to about 10% by weight, up to about 5.8%by weight and up to about 4.5% by weight of crude fiber. Since theamount of crude fiber in commercially available bran can vary it is tobe understood that the term cereal bran as used herein and in the claimsmeans a bran material including not less than about 4.0% by weight ofcrude fiber, crude fiber being the residue left after extraction withpetroleum ether and then (a) boiling with about 1.25% sulphuric acid and(b) boiling with about 1.25% caustic soda, minus ash. Preferably, thebran used in the present invention is one comprising at least about 4.5%by weight of crude fiber.

It will be understood by those familiar with dietary nomenclature thatthe terms "dietary fiber" and "crude fiber", although related, are notequivalent. Generally speaking, for any one product, the latter is lowerthan the former by a factor of about 5. Thus, by way of example, typicalanalyses for coarse wheat bran and middlings may be as follows:

                  TABLE I                                                         ______________________________________                                                     Coarse Bran                                                                            Middlings Bran                                          ______________________________________                                        % Fat          2.75       3.45                                                % Protein      13.55      13.45                                               % Starch       9.2        38.9                                                % Sugars       8.6        7.55                                                % Dietary Fibre                                                                              58.5       32.5                                                % Crude Fibre  10.0       5.6                                                 % Calorific Value                                                                            149        271                                                 Kcals/100 g                                                                   ______________________________________                                    

It will be appreciated from the above discussion that wheat bran onaverage can provide a content of say about 45% by weight of dietaryfiber, although the content of crude fiber provided is much less. In anyevent, however, a snackfood containing about 15% by weight or more ofwheat bran in accordance with the invention will contain a significantand useful amount of dietary fiber.

In putting the present invention into practice it is essential that thedough composition which is finally cooked to produce the snackfoodshould include at least some gelatinized starch. The presence of suchstarch is essential to the formation of an expanded structure, andpreferably the dough should contain at least about 25% by weight ofgelatinized starch based on the total weight of starch, for example,from about 30% to about 70% by weight or higher. Most preferably,however, the dough may contain up to about 100% by weight of gelatinizedstarch based on the total weight of starch.

Furthermore, since high amylolytic activity introduced into the doughthrough the added bran can greatly reduce the content of gelatinizedstarch, that activity must be controlled. In particular, such controlmust be exercised at least subsequent to the formation of a doughincluding both the desired final amount of gelatinized starch and addedbran, and before final cooking to expand the dough to the desiredsnackfood.

It is important to control the effect of amylolytic activity on thecontent of gelatinized starch during the process of making the"half-product" from which the present snackfood is prepared becauseexcessive breakdown of gelatinized starch (once the dough to be cookedhas been prepared) can lead to a product which expands poorly, or not atall, on cooking. Furthermore, such control is also important becauseonce a mixture of a bran with high amylolytic activity together withgelatinized starch and water is formed, and if no control is exercised,the strength and elasticity of the dough become impaired. It thenbecomes difficult, or impossible, to extrude the dough in a continuousmanufacturing process.

In processes which employ ungelatinized starch to give an initialmixture of bran, starch and water, prior to the making of the finaldough composition, it is not necessary initially to treat the bran,since the amylolytic enzymes in raw bran attack ungelatinized starchonly slowly. However, once gelatinized starch is present, it isimportant to control the amylolytic activity of the mixture to preventbreakdown of gelatinized starch either on further processing and/or onstorage.

Such control of the amylolytic activity as is required in thepreparation of the present snackfood, can be exercised in a number ofways. In one aspect of the invention the bran can be treated externallyof the dough, i.e. pre-treated, to reduce its amylolytic activity tobelow a level at which it appreciably decreases the gelatinized starchcontent of the dough. Alternatively, in another aspect of the invention,the bran can be treated internally of the dough to reduce its amylolyticactivity to below a level at which it is detrimental to any gelatinizedstarch present.

Thus, for example, the amylolytic activity of the bran within the doughcan be controlled by mixing the dough under refrigerated conditions,generally wherein the temperature of the dough composition is held at nomore than about 10° C. prior to cooking. In that manner digestion ofgelatinized starch by amylase present in the bran can be kept to aminimum, and the structure of the final snackfood can be maintained.

Preferably, however, the bran is treated to reduce its amylolyticenzyme, e.g. amylase, content (and consequently its amylolytic activity)so as to avoid the necessity to employ refrigeration prior to cooking.In that case it is preferred that any treatment of the bran, whetherbefore or after addition to the dough, should reduce its amylolyticenzyme content to a level where the bran has a maltose value of not morethan about 350 mg/10 g. More preferably, however, the bran is one havinga maltose value reduced to not more than about 250 mg/10 g, e.g. about200 mg/10 g or below, and most preferably not more than about 100 mg/10g.

The treatment of the bran to reduce its maltose value may be effected byany convenient technique. Preferably, however, the amylolytic enzymecontent of the bran is reduced by a heat treatment. A heat treatmentwill destroy enzymes such as amylase and may under certain circumstancesgelatinize residual starch in the bran.

Thus, in one process, the amylolytic activity of the bran may becontrolled by heating the bran before it is added to the doughcomposition. For example, natural or raw bran may be treated by one ofthe following techniques, namely:

(i) By autoclaving at about 120° C. for about 20 minutes.

(ii) By extruding the bran in a heated extruder which heats the bran toabout 160° C. for about 10 seconds.

(iii) By mixing the bran with water to form a slurry, which is thenextruded onto a roller dryer operated at about 100° C., followed bymilling of the dried product to a fine powder.

Alternatively, in another process, whole wheat grain is heated by livesteam at about 100° C. for about 20 minutes. The thus-produced grain onsubsequent milling gives a bran with reduced amylolytic activity.

Additionally or alternatively, the heat treatment of the bran may beeffected after it is added to the dough composition, but before thedough includes its finally required content of gelatinized starch. Inthat case, there is preferably first formed a dough compositioncomprising raw bran and ungelatinized starch, and the dough compositionis heated both to reduce the amylolytic enzyme content of the bran andto gelatinize at least some of the starch in the dough.

A particularly unexpected property imparted to the snackfood of thepresent invention by the incorporation of added cereal bran is theability to have a relatively low fat content compared with known crispsor the like, even when frying is used for cooking. One drawback ofpotato crisps and other fried snackfoods is their high caloric value,and it is a significant advantage of the present snackfood that itscaloric value can be much less per unit weight than other such foods notcontaining bran.

Thus, the present snackfood is advantageous in that it provides a goodsource of fiber in any diet, it is highly palatable, it has a friedflavor, and yet since it can contain fewer calories than comparableknown products not containing bran, it can be produced in a formacceptable to those on weight loss diets.

Subject to what is said above, the expanded snackfood of the presentinvention may be prepared by any process which comprises mixing starch,e.g. wheat flour, and bran, and treating the mixture by any techniquewhich affords the necessary instantaneous, severe, localized heatingconditions to provide discrete cooked portions of said dough expanded tothe necessary level. For example, the snackfood may be prepared by anyof the processing techniques in categories (1) to (3) described above.

Thus, for example, such a process may comprise adding water to a mixtureof bran and ungelatinized starch or a source thereof to form a dough,heating the dough to gelatinize at least some of the starch (and totreat the bran), sub-dividing the resulting dough composition, e.g. byslicing, and drying the subdivided dough to form discrete portions of a"half product" which can be cooked either by frying in fat or oil or,for example, by immersion in heated salt or calcium carbonate. The "halfproduct" can also be made by mixing pre-heated bran with pre-gelatinizedstarch and water to form a dough which is cut or otherwise subdividedand then dried, or by forming a slurry of bran and ungelatinized starchor a source thereof, which is then hot roller dried, and the thus-formedsheet of dried dough sub-divided e.g. cut, into discrete portions. Suchcut portions may be cooked as such or ground, and reconstituted withwater to make a dough, which itself is cut or otherwise sub-divided anddried.

As another example, the process of the invention may comprise forming adough comprising either pretreated and/or raw bran and starch, some ofwhich is gelatinized, extruding the dough through a die under conditionsof temperature and pressure which lead to gelatinization of more of thestarch (and treatment of the bran, if raw bran is used), sub-dividingthe extruded dough into discrete portions, and cooking the portions.

Preferably the snackfood of the invention is prepared by a process usingpre-gelatinized starch suitably in the form of a gelatinized wheat flouror potato flour.

An advantage of employing pre-gelatinized starch is that flavoring andother materials can be incorporated in the dough and there is much lesslikelihood of these materials being destroyed than might be the casewhen the dough is cooked to provide gelatinization.

In order to achieve the necessary expansion, it is desirable that thehalf product prepared in any process employed to produce the snackfoodof the invention should have a moisture content no lower than about 7%by weight. Preferably, however, the moisture content should be fromabout 10% to about 30% by weight, typically about 11% by weight.

In the processes of the invention, frying may be accomplished in hot fator oil, typically hot cooking oil, within the usual temperature range offrom about 160° C. to. about 215° C. In that respect, it is a particularadvantage of the dough used in the present invention that it can becooked at temperatures below the upper end of the range, e.g. at about190 to about 195° C. (typically about 193° C.). This is advantageous inthat the oil will be further from its boiling point and will tend tosmoke less.

Alternatively, "half products", preferably of from about 10 to about 15%moisture content by weight, can be cooked by heating the "half product"by immersion in a bed of hot particulate material such as salt orcalcium carbonate, and separating excess particulate material from theexpanded cooked product. The cooked product can then be sprayed orotherwise treated to incorporate the necessary amount of oil or fatwhich affords the desired flavor.

A variety of additives may be included in the snackfood of the presentinvention to provide the required visual and/or organoleptic properties.Such additives may be included either in the dough, especially in thecase where a pre-gelatinized starch is employed, or by spraying onto thecooked food. Thus, the palatability of the snackfood can be improved byadding flavoring agents, amongst the preferred being salt and vinegar,cheese and/or onion, bacon, meat, fish, tomato, chicken and ham. Suchflavoring agents are commercially available and may comprise hydrolyzedvegetable protein, monosodium glutamate, common salt, spices, syntheticflavors and/or natural flavours, as well as sugar and/or one or moreartificial sweeteners, for example, aspartame, to give the requiredflavor and aroma. Typically up to about 30% by weight of flavoring agentmay be incorporated in the dry mixture from which the dough may beprepared by adding water, and the preferred level is about 10% by weightor lower, for example, 4% by weight.

Currently, Health Authorities are tending towards a policy of wishing tolimit salt in dietary products and the like. Accordingly, if desired asnackfood according to the invention for use in conjunction with alow-salt or salt-free dietary regime may have a "salty" taste providedby the inclusion of potassium and/or ammonium chloride in approximatelythe same amount by weight as (and as a whole or partial substitute for)sodium chloride.

In addition, the snackfood may be supplemented by including aproteinaceous supplement and typically up to about 75% by weight ofproteinaceous material may be incorporated in the dry mixture from whichthe dough is prepared. Typically such proteinaceous materials may bemilk proteins, especially caseinates, soya, wheat and corn gluten. Theinclusion of proteinaceous material improves the nutritional value ofthe snackfood.

To achieve the necessary level of bran in the final product, up to about75% by weight of bran may be included in the dry mixture from which thedough is prepared. However, the especially preferred range forpalatability is from about 30 to about 40% by weight of bran in themixture.

As mentioned above, the expanded snackfood of the present invention cancontain less fat or oil than similar known snackfoods. In particular,typical snackfoods in accordance with the present invention will containno more than about 35%, preferably no more than about 30%, morepreferably no more than about 25%, and still more preferably no morethan about 20% by weight of fat or oil, e.g. about 8 to about 20% byweight fat or oil. Typically also, the moisture content of the finalproduct may be between about 2.5 and about 3% by weight.

The following Table II gives typical bran, fat and moisture contents forsnackfoods in accordance with the present invention compared with asnackfood containing no bran.

                                      TABLE II                                    __________________________________________________________________________    Composition of wheat/bran crisp with different contents of bran               Composition of Crisp .sup.a (% by weight)                                     Bran                                                                          Content of       Wheat        Dietary                                                                            Energy Value                               Dry Mix                                                                             Bran                                                                             Fat                                                                              Flavour                                                                            Flour                                                                             Moisture                                                                           Protein                                                                           Fibre                                                                              Kcal/100 g                                 __________________________________________________________________________     0     0 40 5.5  48.5                                                                              2.5  4.8 1.5  523                                        10     7 30 6.5  51.5                                                                              2.5  6.0 4.5  467                                        20    15 24 7.1  46.9                                                                              2.5  6.8 8.1  405                                        30    24 20 7.5  43.5                                                                              2.5  7.6 12.0 375                                        40    35 13 8.2  38.8                                                                              2.5  8.8 17.0 320                                        50    45  9 8.6  32.4                                                                              2.5  9.5 21.0 285                                        __________________________________________________________________________     .sup.a Assumes Wheat Flour contains 10% by weight protein and 3% by weigh     fibre                                                                         Bran contains 14% by weight protein and 44% by weight fibre              

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following Examples (including a first comparative Example)illustrate the preparation of expanded snackfoods according to thepresent invention. All of the expanded snackfoods described have an oilor fat content of at least about 5% by weight and are expanded to atleast about 1.25 times the volume of the original dough portions. Also,in each case the bran used is a middlings bran having an analysis as setout in Table I above.

Example 1

In order to compare the results obtained with raw and treated bran, adough composition was prepared from the following ingredients, usingthree different types of bran:

    ______________________________________                                        Water                700    mls                                               Potato starch        580    g                                                 Bran                 600    g                                                 Potato flour         40     g                                                 Palm oil             14     g                                                 Salt                 40     g                                                 ______________________________________                                    

Doughs having the above composition were prepared by first mixing thestarch only with the water. The mixing was effected at about 90° C. in amixing bowl immersed in a container of water at about 90° C., therebyforming a hot water jacket to minimize heat loss during mixing, for aperiod of about 5 minutes, which permitted the starch visibly to gel.The other ingredients were then added and the whole mixed for a further15 minutes in a Hobart mixer. Finally, the mix was extruded through aplate with three-eighths of an inch diameter holes.

The dough compositions produced and extruded were as follows:

Composition A in which the bran was raw bran having a maltose value ofabout 550 mg/10 g;

Composition B in which the bran was a partially-heatedcommercially-available product having a maltose value of about 186 mg/10g and a moisture content of about 12.4% by weight; and

Composition C in which the bran was a specially heat-treated branautoclaved at about 120° C. and under about 15 psi of pressure for about20 minutes, and having a maltose value of about 90 mg/10 g and amoisture content of about 10.3% by weight.

Composition A produced with the raw bran was very sticky. Moreover, itproved impossible to extrude properly and there were visible signs ofstarch liquefaction. On the other hand Composition B produced withpartially-heated bran extruded satisfactorily and was not sticky,although the strand elasticity was only fair and the strands brokerather easily.

However, with Composition C produced using the fully heat-treated bran,a much better extruded material was obtained, of good gel strength andelasticity, with strands of about 1 meter in length and capable ofholding their own weight without breaking.

In addition, two further dough mixes were produced as described above,one mix being produced using the bran used for composition B and theother mix being produced using the same bran, but after it had beenautoclaved at about 120° C. and about 15 psi for about 20 minutes. Eachmix was divided into two portions, one portion being placed in apolythene bag and the other portion being extruded as before. Thesamples from each of the two mixes that had been placed in polythenebags were incubated for about two hours at about 40° C., after whichthose too were extruded as before.

A comparison of the extruded material after incubation with the materialextruded without delay showed there was little difference in thefully-heated bran mix, but a significant difference in thepartially-heated bran mix, as exhibited by a marked lowering of thestrength and elasticity of the extruded strands with time.

In each case, the half-product produced on extrusion using unincubatedComposition B or Composition C whether incubated or not could be cookedto produce a suitable snackfood in accordance with the invention, forexample, by frying in hot vegetable fat at about 193° C. for about 10seconds.

Furthermore, two other dough mixes were produced as described above,this time with brans of maltose value 350 mg/10 g and 450 mg/10 grespectively. On incubation for various time periods, the results givenin Table III below were obtained:

                  TABLE III                                                       ______________________________________                                                   Dough including                                                                              Dough including                                     Incubation time                                                                          bran of maltose                                                                              bran of maltose                                     at 40° C.                                                                         value 350 mg/10 g                                                                            value 450 mg/10 g                                   ______________________________________                                        Nil        Extruded evenly                                                                              Extruded evenly                                                and cleanly -  and cleanly -                                                  dough strength dough strength                                                 and elasticity and elasticity                                                 only fair      poor                                                30 minutes Sticky giving  Extruded poorly -                                              uneven extrusion -                                                                           dough of very                                                  dough of poor  poor strength and                                              strength and   elasticity and                                                 elasticity -   very sticky                                                    strands adhered                                                               to one another and                                                            were of sticky                                                                texture                                                            1 hour     Extruded with  Very difficult to                                              difficulty -   extrude - strands                                              strands very   very sticky with                                               sticky and of  no strength or                                                 insufficient   elasticity - broke                                             strength or    up and adhered to                                              elasticity not one another                                                    to break                                                           2 hours    Very difficult to                                                                            Would not extrude -                                            extrude - strands                                                                            consistency resem-                                             inseparable and                                                                              bling porridge                                                 very sticky with                                                              no strength                                                        ______________________________________                                    

It is to be noted here that all of the maltose values referred to hereinand in the claims are measured by the method of Blish and Sandstedt(1933)--see, for example, "Modern Cereal Chemistry" (1967)--Kent, Jonesand Amos--and "Pearsons Chemical Analysis of Foods", 1981. Since thereare other methods which employ different principles and units e.g. thoseof Rumsey (pre 1933) and Hildebrand and McClellan (1938), it isimportant to note the method and units employed in the presentinvention.

In the next following Examples, various preparative processes areillustrated using either a mix containing pre-heated bran andgelatinized starch, or a mix initially containing raw bran andungelatinized starch, together with a process step in which both thebran and starch are heated to reduce amylolytic activity of the formerand at least partially to gelatinize the latter.

(A) EXAMPLES OF DRY COLLET PROCESSES Example 2

A mix was made of the following ingredients:

    ______________________________________                                        Gelatinized wheat flour  60 g                                                 Flavouring               10 g                                                 Wheat bran (pre-heated)  30 g                                                 ______________________________________                                    

To 100 g of this mix were added 80 ml of water and the whole mixed wellinto a dough. The dough was formed into a cylindrical rod of 25 mmdiameter and cut into thin slices 1 mm thick. The latter were dried in awarm room overnight. The dried slices were then cooked in hot vegetablefat at 193° C. for about ten seconds.

Example 3

A mix is made of the following ingredients:

    ______________________________________                                        Gelatinized wheat flour  60 g                                                 Flavouring               10 g                                                 Wheat bran (pre-heated)  20 g                                                 Soya protein isolate     10 g                                                 ______________________________________                                    

A snackfood is prepared from this mix as described in Example 2.

Example 4

Potato flour is produced by washing and peeling raw potatoes, thenboiling and mashing them after straining and rejecting the water. Themashed potato is rolled dry over hot rollers as a powder of moisturecontent about 4 to about 5%. Wheat starch in fine powder form and wheatbran are mixed with the potato flour in the following proportions:

    ______________________________________                                        Potato flour             20 g                                                 Wheat starch             40 g                                                 Bran (unheated i.e. raw) 30 g                                                 ______________________________________                                    

Sufficient water is added to make a dough (80 ml). The dough is extrudedinto a cylindrical rod, cut into lengths of about 30 cm, placed inboiling water and allowed to boil for 45 minutes at least partially togelatinize starch and to reduce the amylolytic activity of the bran. Thegelatinized product is cut with a sharp knife into thin wafers, whichare then dried in a warm room overnight. The slices are fried in oil at193° C.

Example 5

The following ingredients are intimately mixed according to the formulabelow:

    ______________________________________                                        Potato granules (gelatinized)                                                                           30 g                                                Potato starch (non-gelatinized)                                                                         30 g                                                Pre-gelatinized potato starch                                                                            7 g                                                Wheat bran (pre-heated)   30 g                                                Salt                       3 g                                                ______________________________________                                    

The ingredients are mixed for 8 minutes in a vertical mixer and themoisture content adjusted to about 35% by weight by addition of water.After mixing, the material is extruded through a standard pasta press ata temperature of from 55 to 65° C. and at a pressure of from 90 to 110Kg/cm². The die produced spiral shaped pieces approximately 30 mm inlength and 1 cm in diameter, with a wall thickness of 1 mm. Afterextrusion, the pellets are slowly dried in a drum drier at a temperatureof from 35 to 55° C. for about 6 hours. The final moisture content ofthe "half product" is about 11% by weight. The "half product" is friedin oil at 205° C. for about 15 seconds.

Example 6

The following ingredients are mixed at 55° C. for 20 minutes into aslurry:

    ______________________________________                                        Potato flour             20 g                                                 Wheat bran (unheated)    20 g                                                 Flavouring                5 g                                                 Water                    55 g                                                 ______________________________________                                    

The slurry is extruded onto a roller dryer operated at 100° C. togelatinize starch and to reduce the amylolytic activity of the bran. Thedrums are allowed to rotate for 1 minute until a film of approximately0.5 mm thickness has built up. The multi-layer film is removed as asheet with a blade and cut into 2.5 cm×4 cm rectangles and dried toabout 11% by weight moisture. These are deep fried for 10 seconds in fatat 170° C.

In the above Example the potato flour can be replaced by pea or wheatflour.

Example 7

The above Examples are repeated except that the dried "half product" iscooked by immersion in hot particulate salt instead of by frying toproduce a cooked, but fat-free product. For each repeat Example, asnackfood having an oil content of a magnitude which gives a palatableproduct is produced from the cooked product by spraying with a vegetableoil. In this way there are produced five batches of snackfood havingrespectively an oil content of 35%, 30%, 25% and 15% by weight.

(B) EXAMPLES OF FRYING WET COMPLETELY GELATINIZED DOUGH Example 8

A mix is made as described below of the following ingredients:

    ______________________________________                                        Potato granules (gelatinized)                                                                          600 g                                                Isolated soya protein    300 g                                                Wheat bran (pre-heated)  300 g                                                Salt                      60 g                                                Glycerol monostearate     20 g                                                Water                    700 g                                                ______________________________________                                    

The water, salt and glycerol monostearate are mechanically blended andthe remaining dry ingredients mixed in a Hobart mixer. The wet blendedingredients are then added to the dry mixed ingredients and mixed untilthe mass is free flowing. The mixture is then extruded in a press usinga 1.25 mm by 2.5 cm ribbon die at a temperature of 74° C. The extrudedribbon is stretched by from 30 to 40% and cut into 3 cm lengths andfried at 190° C. for 45 seconds.

Example 9

A potato dough is made from the following composition:

    ______________________________________                                        Potato granules (gelatinized)                                                                          70    g                                              Wheat bran (pre-heated)  27    g                                              Guar gum                 1.5   g                                              Salt                     1.5   g                                              ______________________________________                                    

The above dry ingredients are mixed together and then uniformly mixedwith about 226 ml water at 60° C. to form a dough slurry of about 30% byweight solids content. The dough is fed through a piston extruder with adie of 1 cm×1 cm and cut into portions 7.5 cm long. The cut portions aredischarged into a deep fat fryer at 170° C. for about 90 seconds. Thepart-fried material is stored deep frozen until required. To prepare forconsumption the frozen portions are toasted in a standard bread toasterfor from 1 to 3 minutes.

Example 10

The process of Example 9 is repeated, except that raw bran is usedinstead of heated bran, and the temperature of the dough slurry is keptbelow 10° C. by refrigeration. The dough is fed through a pistonextruder and fried as before.

Example 11

The following ingredients are mixed in a Hobart mixer to form a dough:

The dough at a temperature of 45°C. is passed through a two roll mill togive a sheet 0.4 mm thick which is cut into elliptical pieces of 7.5 cm×5 cm diameter. These are deep fried in cottonseed oil at 175°C.

    ______________________________________                                        Potato flakes (gelatinized)                                                                            200 g                                                Bran (pre-heated)        100 g                                                Hydrolysed soyabean oil*  5 g                                                 Ascorbic acid             1 g                                                 Water                    200 g                                                ______________________________________                                         *containing 40% monoglycerides, 40% diglycerides and 20% triglycerides.  

Example 12

A mix is made of 97% by weight of tapioca and 3% by weight of salt.About 700 g of the mix are then cooked with 300 ml of water in apressure cooker. The cooked dough is extruded through holes 3 mmdiameter and cut into pellets 1.5 mm to 3 mm length. The pellets arethen mixed with dehydrated mashed potatoes and bran as follows:

    ______________________________________                                        Pellets (32% by weight moisture)                                                                        25 g                                                Mashed potato (gelatinized)                                                                             25 g                                                Bran (pre-heated)         25 g                                                Water                     18 g                                                ______________________________________                                    

The overall moisture content is 32% by weight.

The mixture is finely chopped and blended and the granular material fedthrough rollers to form a sheet 0.75 mm thick from which ellipticalshaped chips are cut. These are fried in coconut oil at 200° C. for 15to 20 seconds.

(C) EXAMPLES OF FRYING A WET DOUGH CONTAINING SOME UNGELATINIZED STARCHExample 13

The following ingredients are combined in a 5 quart Hobart mixer using apaddle turning at low speed for 1 minute:

    ______________________________________                                        Dried potato flakes (gelatinized)                                                                       100 g                                               Potato starch (ungelatinized)                                                                           100 g                                               Wheat bran (pre-heated)   100 g                                               Salt                       7 g                                                ______________________________________                                    

During an additional one minute, 347 mls of water at room temperatureare added and mixing continued for one minute thereafter. The mixture isthen placed in a piston extruder. By application of force, the mixtureis extruded through a die opening of 2.5 cm by 1 mm dimensions. Theextruded dough is cut with a knife into pieces approximately 5 cm long,and as cut the pieces are allowed to fall into a standard fryercontaining hydrogenated vegetable oil at 190° C. where they are friedfor 90 seconds.

In the above Example, potato starch can be replaced by tapioca starchwith excellent results.

I claim:
 1. An expanded snackfood prepared from cereal bran of the typethat has amylolytic activity and prepared from a dough composition ofpredetermined volume and comprising cooked portions of dough compositioncomprising gelatinized starch and added cereal bran selected from thegroup consisting of wheat bran, barley barn, oat bran, rye bran, maizebran and mixtures thereof, the snackfood containing from about 5% toabout 35% by weight of oil or fat and from about 10% to about 70% byweight of bran, and having a volume at least about 1.25 times saidpredetermined volume, the amylolytic activity of the bran beingcontrolled to minimize breakdown of gelatinized starch in the doughcomposition subsequent to formation of the dough composition to becooked and up to cooking of the dough.
 2. A snackfood according to claim1 wherein the amylolytic activity of the bran is controlled by selectinga bran having a maltose value of not more than about 350 mg/10 g.
 3. Asnackfood according to claim 1 wherein the amylolytic activity of thebran is controlled by selecting a bran having a maltose value of notmore than about 100 mg/10 g.
 4. A snackfood according to claim 1 whereinthe amylolytic activity of the bran is controlled by mixing, and ifnecessary, holding the dough under conditions wherein the temperature ofthe dough composition is held at no more than about 10° C. prior tocooking.
 5. A snackfood according to claim 1 wherein the amylolyticactivity of the bran is controlled by heating the bran before it isadded to the dough composition.
 6. A snackfood according to claim 1wherein the amylolytic activity of the bran is controlled by heating thebran after it is added to the dough composition, but before the doughincludes its finally required content of gelatinized starch.
 7. Asnackfood according to claim 1 wherein said volume is at least about 1.5times said predetermined volume.
 8. A snackfood according to claim 7wherein said volume is at least about 2 times said predetermined volume.9. A snackfood according to claim 8 wherein said volume is at leastabout 3 times said predetermined volume.
 10. A snackfood according toclaim 8 including about 15 to about 70% by weight of bran.
 11. Asnackfood according to claim 10 including about 20 to about 50% byweight of bran.
 12. A snackfood according to claim 1 including about 30to about 70% by weight of gelatinized starch based on the total weightof the starch.
 13. A snackfood according to claim 1 including 100% byweight of gelatinized starch based on the total weight of the starch.14. A snackfood according to claim 10 including 100% by weight ofgelatinized starch based on the total weight of the starch.